const btn = document.getElementById('modeBtn');
btn.addEventListener('click',(e)=>{
    const body = document.body;
    if(e.target.innerHTML==='test1'){
        body.style.color='white'
        body.style.backgroundColor = 'black';
        body.style.innerHTML = 'test2'
    } else {
        body.style.color='black'
        body.style.backgroundColor ='white';
        body.style.innerHTML = 'test1'
    }
})